1. Field
This disclosure relates generally to integrated circuits, and more specifically, to making non-volatile memories.
2. Related Art
Non-volatile memories (NVMs) have a number of reliability issues such as data retention, operational life, program disturb, and read disturb. To a large extent, reliability is related to the number of program/erase cycles that have been performed on the NVM. For some uses only a few thousand cycles may be sufficient, but many uses require hundreds of thousands of program/erase cycles and some even into the millions. A single program/erase cycle of an entire NVM can easily take nearly 10 seconds because of the relatively slow program and erase operations and the large number of cells that are present in typical NVMs. For example, greater than 8 megabits is not uncommon. Accordingly, it can take weeks just to perform the requisite number of program/erase cycles for one of the reliability tests. This can significantly slow down development of new NVM designs as well as product qualifications. There is considerable effort in testing new designs of device structures that have primary significance in the reliability of an NVM. For example, the design of the gate dielectric between a floating gate and a substrate of an NVM is very significant to reliability especially those aspects of reliability related to the number of program/erase cycles.
Accordingly there is a need to determine reliability without having to perform large quantities of program/erase cycles.